Update dependencies for codegen

[morr0ne]

Simple pr that updates the depedencies of the codegen code.

• tempdir: The tempdir crate has been deprecated and has not seen any updates in over six years. I have replaced it with the tempfile crate, which seems to be the successor to tempdir, as its functionality has been merged into tempfile.

• bindgen: The bindgen crate has been updated to the latest version. While the update introduces only minor improvements, it reduces the number of dependencies and addresses known security vulnerabilities

The only noticeable changes in the generated code are a version header update and what appears to be a more accurate implementation of Clone for unions.

Although these changes may seem minor, they provide a measurable, albeit small, improvement in compile time, especially in some of my older devices. It also just seems like good practice, I see no reason why this dependencies should not be kept up to date

[sunfishcode]

Thanks!